FIXING AND DEVELOPING.
Suppose now that four prints are given identical exposure in the proportion of six times that required for an ordinary print, and are then developed as above, and that one of them is removed to the fixing bath in the yellow stage, another in the red stage, and another in the green ; they will first of all undergo a change of colour in the fixing bath, but on drying they will regain the colour which they possessed when they left the developer. For this purpose make up the following : (No. 3) Ammonium bromide, 1 oz. ; am monium carbonate, 1 oz. ; water, 21) oz. It is essential that the carbonate of ammonia should be in clear lumps. If it is covered with white powder it should be discarded. Carbonate of ammonia must he kept in a well-stoppered bottle, or the ammonia will be lost. The method given is practic ally that recommended by the Paget Prize Plate Co. for use with their " Gravura " paper, with which excellent results have been secured. The formula, for develop ment is as follows :—For warm sepia : Nor mal developer, 1 oz. ; restrainer, 1 dram ;
water, 6 oz. For red: Normal developer, 1 oz. ; restrainer, 4 drams ; water 1 pint. The normal developer is :—Hydroquinone, 53 grs. ; metol, 14 grs. ; soda sulphite, 1 oz. ; soda carbonate, 1.1 oz. ; potassium bromide, 2 grs. ; water, to 20 oz. The length of time occupied in development will vary greatly. In the case of red, the development some times takes six or seven minutes. Whether the desired colour will have been obtained at the same time as the appearance of the correct amount of detail is a matter which is regulated by exposure, and must he found by experiment. Exposure in sec tions, as before recommended, will be advisable. A warm sepia usually requires about six times as much as is needed for the ordinary colour, and a red print eight to ten times. If the exposure is insuffi cient, the colour will be greenish by pro longed development. To obtain any given colour with certainty and precision e quires some skill and experience.